An in vitro comparison of diagnostic accuracy of cone beam computed tomography and phosphor storage plate to detect simulated occlusal secondary caries under amalgam restoration

Abstract

Background: This study was aimed to compare the diagnostic accuracy and feasibility of cone

beam computed tomography (CBCT) with phosphor storage plate (PSP) in detection of simulated

occlusal secondary caries.

Materials and Methods: In this in vitro descriptive-comparative study, a total of 80 slots of class I

cavities were prepared on 80 extracted human premolars. Then, 40 teeth were randomly selected

out of this sample and artifi cial carious lesions were created on these teeth by a round diamond

bur no. 1/2. All 80 teeth were restored with amalgam fi llings and radiographs were taken, both

with PSP system and CBCT. All images were evaluated by three calibrated observers. The area

under the receiver operating characteristic curve was used to compare the diagnostic accuracy of

two systems. SPSS (SPSS Inc., Chicago, IL, USA) was adopted for statistical analysis. The difference

between Az value of bitewing and CBCT methods were compared by pairwise comparison method.

The inter- and intra-operator agreement was assessed by kappa analysis (P < 0.05).

Results: The mean Az value for bitewings and CBCT was 0.903 and 0.994, respectively. Signifi cant

differences were found between PSP and CBCT (P = 0.010). The kappa value for inter-observer

agreement was 0.68 and 0.76 for PSP and CBCT, respectively. The kappa value for intra-observer

agreement was 0.698 (observer 1, P = 0.000), 0.766 (observer 2, P = 0.000) and 0.716 (observer 3,

P = 0.000) in PSP method, and 0.816 (observer 1, P = 0.000), 0.653 (observer 2, P = 0.000) and

0.744 (observer 3, P = 0.000) in CBCT method.

Conclusion: This in vitro study, with a limited number of samples, showed that the New Tom VGI

Flex CBCT system was more accurate than the PSP in detecting the simulated small secondary

occlusal caries under amalgam restoration.

Key Words: Cone-beam computed tomography, dental caries, dental radiograph, digital radiograph